In version 3.33 of CURL, there were significant changes to the way OAuth2 tokens are requested.
To request the token, you must use the appropriate command.
See the example below:
curl -d "grant_type=client_credentials&client_id=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx&client_secret=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" "https://xxx.xxx.xxx.xxx/iso/oauth2/token" -s --show-error -X POST -k
Make sure to replace xxxxxxxxx with the correct client_id and client_secret values, and adjust the URL to the desired endpoint.